v3.26.1
Contents of Significant Accounts - Details of Investments Accounted for Under the Equity Method (Detail)
$ in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2025
TWD ($)
Dec. 31, 2024
TWD ($)
Dec. 31, 2025
USD ($)
Investments in associates and joint ventures [line items]      
Amount $ 36,869,092 $ 33,274,869 $ 1,175,298
SILICON INTEGRATED SYSTEMS CORP. (SIS) [member]      
Investments in associates and joint ventures [line items]      
Amount $ 2,264,435 $ 1,922,753  
Percentage of ownership or voting rights, Associates 17.99% 19.02%  
FARADAY TECHNOLOGY CORP. (FARADAY) [member]      
Investments in associates and joint ventures [line items]      
Amount $ 2,489,096 $ 2,484,001  
Percentage of ownership or voting rights, Associates 13.80% 13.80%  
UNIMICRON TECHNOLOGY CORP. (UNIMICRON) [member]      
Investments in associates and joint ventures [line items]      
Amount $ 14,388,815 $ 13,824,584  
Percentage of ownership or voting rights, Associates 13.01% 13.01%  
MTIC HOLDINGS PTE. LTD. [member]      
Investments in associates and joint ventures [line items]      
Amount $ 0 $ 0  
Percentage of ownership or voting rights, Associates 45.44% 45.44%  
UNITECH CAPITAL INC. [member]      
Investments in associates and joint ventures [line items]      
Amount $ 524,403 $ 556,610  
Percentage of ownership or voting rights, Associates 42.00% 42.00%  
TRIKNIGHT CAPITAL CORPORATION (TRIKNIGHT) [member]      
Investments in associates and joint ventures [line items]      
Amount $ 759,446 $ 1,298,112  
Percentage of ownership or voting rights, Associates 40.00% 40.00%  
HSUN CHIEH CAPITAL CORP. [member]      
Investments in associates and joint ventures [line items]      
Amount $ 233,438 $ 266,066  
Percentage of ownership or voting rights, Associates 40.00% 40.00%  
PURIUMFIL INC. [member]      
Investments in associates and joint ventures [line items]      
Amount $ 0 $ 12,340  
Percentage of ownership or voting rights, Associates 0.00% 40.00%  
HSUN CHIEH INVESTMENT CO., LTD. (HSUN CHIEH) [member]      
Investments in associates and joint ventures [line items]      
Amount $ 4,855,031 $ 4,723,930  
Percentage of ownership or voting rights, Associates 36.49% 36.49%  
YANN YUAN INVESTMENT CO., LTD. (YANN YUAN) [member]      
Investments in associates and joint ventures [line items]      
Amount $ 11,231,446 $ 8,044,460  
Percentage of ownership or voting rights, Associates 26.78% 26.78%  
UNITED LED CORPORATION HONG KONG LIMITED [member]      
Investments in associates and joint ventures [line items]      
Amount $ 122,982 $ 101,468  
Percentage of ownership or voting rights, Associates 25.14% 25.14%  
VSENSE CO., LTD. (VSENSE) [member]      
Investments in associates and joint ventures [line items]      
Amount $ 0 $ 0  
Percentage of ownership or voting rights, Associates 0.00% 23.98%  
TRANSLINK CAPITAL PARTNERS I, L.P. [member]      
Investments in associates and joint ventures [line items]      
Amount $ 0 $ 40,545  
Percentage of ownership or voting rights, Associates 0.00% 10.38%